A radiation image detector including a charge generation layer, and a detection layer including: many pixels, each having a collection electrode for collecting charges generated in the charge generation layer, a storage capacitor for storing charges collected by the collection electrode, and a TFT switch for reading out charges from the storage capacitor; many scanning lines; and many data lines. Each storage capacitor is formed between a storage capacitor electrode connected to the drain electrode of a TFT switch and the scanning line connected to a TFT switch adjacent to the TFT switch to which the drain electrode belongs, an array of the TFT switches is divided into upper and lower halves, each data line is divided into upper and lower halves, and a dummy wire is provided at the division boundary for forming a storage capacitor of a pixel disposed at the division boundary section.